Septomarginal trabecula and anterior papillary muscle in primate hearts: developmental issues.

The septomarginal trabecula is present in all human hearts as well as in the hearts of other primates. It usually connects the interventricular septum with the anterior papillary muscle, although there are many variations in how this is achieved. The object of the analyses was to estimate the bilateral topography of the septomarginal trabecula and the anterior papillary muscle in the context of the ontogeny and phylogeny of primates. A total of 138 hearts were examined from number of different non-human primates. The presence of the septomarginal trabecula was confirmed in 94.9% of cases, although not in the hearts of Lemur varius. Four configurations could be distinguished by defining the location of the septomarginal trabecula and its relation to the anterior papillary muscle.For the hearts of the Strepsirrhini and the majority of Platyrrhini neither structure was related, whereas in all examined representatives of Homino idea they had fused and created morphologically varying forms. On the basis of these results,a concept was developed for the sequence of changes which the topography of the septomarginal trabecula and the anterior papillary muscle undergo during ontogeny and phylogeny.

Myocardial bridges in domestic pig--morphological aspects.

The morphology of myocardial bridges (MB) in the heart of the domestic pig remain an open issue. Despite numerous analyses of the subject, many controversies still exist. Opinions also differ when the influence of the MB on haemodynamic processes in the coronal vessel system is concerned. In the examined group of 150 domestic pig's hearts, the length of the detected MB varied from 1.8 to 39.7 mm while their thickness amounted to 0.8 - 4.7 mm. Both the longest and the thickest bridges were connected with the posterior interventricular branch. It was noticed that the MB muscle bands cross the long axis of the vessels located in the grooves mostly at almost a right angle. Three forms of perivascular space were educed using the criterion of the distance of the vessel from the surrounding muscularis externa.

Positions of septal papillary muscles in human hearts.

Septal papillary muscles, similarly to other papillary muscles, are essential elements of the heart valvular system. Damage to their structure may lead to a considerable life risk. Of all the papillary muscles, the septal papillary muscles are characterized by the greatest topographical and morphological variability. However, information about these muscles is scarce and fragmentary. The objective of this study was to ascertain their occurrence and the region in which they are placed in the inter-ventricular septum. One hundred and eleven human hearts were examined. The hearts belonged to the Clinical Anatomy Department of the Medical University of Gdansk. They were fixed in formalin with ethanol and came from middle-aged and older individuals of both sexes, devoid of pathological changes and birth defects. During the tests, classic anatomical methods were applied. The region where the papillary muscles are found covers a sizeable surface of the septum, from the conus arteriosus up to the back angle of the right chamber. Depending on their location the following septal papillary muscles (musculi papillares septales, MPS) were singled out: 1) lying on the front wall of the septum (anterior papillares septales), 2) in the central part of the septum (central muscles), and 3) in the posterior section of the septum (posterior papillares septales). A trial to determine the types of MPS was based on this diversity of location. Consequently, five types of MPS were specified: type I: anterior-central (44.1%); type II: anterior (15.3%); type III: anterior-posterior (13.5%); type IV: anterior-central-posterior (24.3%); and type V: uniform (2.75%). This study is an attempt to systematize and standardize the terminology of these structures.

Distribution of myocardial bridges in domestic pig.

Localisation and morphology of myocardial bridges in the heart of domestic pig remain an open issue. Since these structures significantly influence haemodynamics in the coronary arteries, their occurance may lead to numerous pathologies. In the examined group of 150 domestic pig's hearts, myocardial bridges were diagnosed in 47.3% of the material, mostly in males. In majority of cases the bridges were present above the posterior interventricular branch of the right coronary artery, less often above the anterior interventricular branch of the left coronary artery, and seldom above other blood vessels. The presence of myocardial bridges usually referred to the medial and initial segments of the arteries examined.

Microscopic study of right fibrous annulus.

The term annulus fibrous is still used in anatomical and clinical terminology but does not exist in anatomical nomenclature. This structure is proposed as an anatomical substrate for circus movement of excitation. Multiple cardiac damage after blunt chest trauma is rare, but usually affects the septal part of the right fibrous annulus. Histological observation confirms the results of our previous macroscopic study and shows that the most stable part of fibrous annulus is the septal part and the region of anterior angle of the right ventricle, and the most labile parts are the lateral and posterior angles of the right ventricle and the posterior part of the fibrous annulus. Our histological study shows that the right fibrous annulus is a heterogeneous structure and may play a role in changes of shape of the right atrio-ventricular ostium during human life.

The relationship between the membranous part of the interventricular septum and the septal part of the attachment of the tricuspid valve in adult human hearts.

The membranous septum is a difficult structure to demonstrate in vivo. It is possible to measure its dimensions in a cadaver after the introduction of light into the aorta, but difficult to do so otherwise. The present study was performed on a group of 107 formalin-fixed adult hearts from both sexes and 18-90 years of age. The hearts were divided into groups depending on sex and age. The length of the septal part of the attachment of the tricuspid valve was divided by the length of the supravalvular part of the membranous interventricular septum.

Morphometric features of the right atrioventricular orifice in adult human hearts.

The normal data of the tricuspid valve complex is of great clinical importance in the light of progress in cardiosurgery and the development of novel operating techniques. A range of measurements for the right atrioventricular orifice in 96 human adult hearts was examined by means of anatomical dissection, inspection, examination, and statistical analyses. The length of the attachment of the anterior leaflet increased significantly between group I (aged 18-40 years) and group II (aged 41-64 years) in women only. In men there were no significant differences in this parameter between any of the three age groups. In addition, the attachment length of the posterior leaflet in women increased statistically in the second age group. In men, in contrast, the attachment length of the posterior leaflet did not increase significantly between the first and second age groups and became significantly larger only in oldest age group, consisting of men aged over 65. No statistically significant differences between the three age groups were found for the attachment length of the septal leaflet (p>0.05). In female hearts significant increases in the frontal and sagittal dimensions of the tricuspid valve orifice were observed between the second age group and the group aged over 65. In male hearts both the frontal and sagittal dimensions increased significantly with advanced age. The right atrioventricular orifice expressed as the ellipse area was statistically greater than the triangular area (p<0.01) in each age group. It should be noticed that both areas increased significantly during ageing. This study has demonstrated that the shape of the right atrioventricular orifice evolves during life, from a triangular shape to a more elliptical shape.

The initial zones of the atrioventricular node: really neglected anatomical features of potential clinical significance?

The constant evolution of medical knowledge and accompanying development of diagnostic and treatment possibilities for arrhythmias and conduction disturbances has reawakened interest in the structure and function of the conduction system of the human heart, especially in the region of the atrioventricular (AV) junction and within the junction itself. Of the large number of studies dealing with the AV junction few focus on the initial zones of the AV node. These were described for the first time by Tawara in 1906. Similarly, Anderson et al. distinguished two origins of the AV node, the left one running towards the basis of the mitral valve and the right one leading towards the tricuspid valve. The differences in length and scale could be the result of the adoption of different reference points. The study was carried out on the material of 50 human hearts, of both sexes and ranging in age from 22 to 93, which were fixed in 10% formalin and 98% ethanol solution. The tissue obtained was fixed in the 10% formalin solution and, after being sunk in the paraffin, was cut into layers of about 10 mum thick. According to the age of the hearts, every 10(th) or 6(th) section was stained by the Masson-Goldner method. The preparations were examined under a LEICA 2000 and BIOLAR 2 microscope at magnifications of 2x to 400x. Each of the 50 examined hearts contained the atrioventricular node and its initial parts. We observed that the initial zone of the AV node is created by an assembly of cells typical for a conduction system that can create three groups that are initially independent of each other and are always arranged around the AV nodal artery. In all the hearts examined we found at least two initial parts of the node: the superior and inferior. These two groups were present in 45 hearts (90%). In the last 5 cases (10%) there was also a middle group. No cases were found either with a single initial group or without any initial groups. In the sections examined the superior group appeared to be first in 27 hearts (54%), while in 23 cases (46%) the inferior group was first. The length of each group was measured from its first appearance to its first direct contact with the second part. The length of the superior part varied from 0.15 to 2.91 mm (mean 0.90 +/- 0.6 mm), the inferior from 0.11 to 2.41 mm (mean 0.88 +/- 0.6 mm) and the middle from 0.67 to 2.21 mm (mean 1.04 +/- 0.7 mm). As mentioned above, in all 50 hearts there was a direct connection between the atrial muscle and the upper origin of AV node. Furthermore, in all sections (100%) the same part of the interatrial septal muscle was connected to the compact part of the node. Additionally, in 3 cases (6%) we were able to observe direct connections between the muscle fibres running from the fasciculus limbicus inferior to the initial zone of the AV node: in 2 cases (4%) with the superior group and in 1 case (2%) with the inferior group. In 8% of the material the atrial muscle of the supra-orificial zone made direct contact with the superior initial group and the compact zone of the node and in 10% there was contact between the suborificial muscle and the inferior group and the compact part of the node. This configuration was not observed in relation to the middle and inferior groups.

The morphology and distribution of the tendinous chords and their relation to the papillary muscles in the tricuspid valve of the human heart.

The tendinous chords of the tricuspid valve are the predominant type of connection between the papillary muscles and the tricuspid valve. Studies describing the evolutionary line of these connections are well known. The flexibility of particular leaflets of the tricuspid valve varies, as does the tension of the blood stream in particular cusps. The present study was performed on a group of 96 formalin-fixed adult human hearts, which ranged in age from 18 to 90 years and gave no evidence of congenital malformations or pathological changes. The valves were divided into five types according to earlier studies and analysis was made in terms of these types. The tendinous chords and their ramifications were counted. The surfaces of particular leaflets were measured. The ratio of marginal to ventricular leaflets was counted for each type of leaflet in particular types of valves. The parts of the main leaflets supported by specific papillary muscles were counted for types 1, 2 and 3. The number of tendinous chords decreased in leaflets in particular types of tricuspid valve, but the ratio of chords attached to the margins and ventricular surfaces was similar. The number of chords for the surface of leaflets (measured in mm2) was similar in particular types of valve for all cusps. The most differentiated were commissural chords in all types of valve. The ratio of chords attached to the margins and ventricular surfaces does not depend on the surface area of the leaflets.

The morphometry of the accessory leaflets of the tricuspid valve in a four cuspidal model.

The tricuspid valve is of great importance because of the progress made in operative techniques and invasive cardiology accidents. This structure is more differentiated during evolution than the mitral valve. Accessory leaflets, their frequency and role are still controversial, despite the fact that they have been known from the beginning of the 20th century. The number of leaflets in the tricuspid valve grows in an evolutionary line, but the rules governing their appearance are still not known. The samples were taken from a group of 107 human adult hearts. The four-cuspidal form of the tricuspid valve was used as the simplest model to show the appearance of accessory leaflets for anatomical and statistical examination. On the basis of the results of this study we conclude that the separation of accessory leaflets is a complex process.

The connection between the papillary muscles and leaflets of the tricuspid valve.

The tricuspid valve is more differentiated during evolutionary development than the mitral valve. In birds it is a muscular structure joined directly to the papillary muscles, although the mitral valve of birds resembles that of mammals. There have been well-known studies describing the evolutionary line of connection of the tricuspid valve with the papillary muscles. The present study was performed on a group of 107 formalin-fixed adult human hearts. The valves and papillary muscles were classified according to a scheme for human hearts drawn up earlier. The types of connection between leaflets of the tricuspid valve and the papillary muscles were classified according to a scheme drawn up earlier for vertebrates. We observed 3 types of connection between leaflets of the tricuspid valve and the papillary muscles in the group studied. The muscular and membranous connections were not linked with any one type of tricuspid valve. Atypical forms of distribution of the tendinous chords of the right ventricle were observed. It was found that valves with a higher number of leaflets were (with the exception of type 0) provided with a smaller number of tendinous chords. Atavistic features and atypical forms of distribution of the tendinous chords are present in a small percentage of samples of the human right valvular apparatus.

Basic axes of human heart in correlation with heart mass and right ventricular wall thickness.

A comparison of the data published in anatomy textbooks and anthropological tables does not reveal any change in basic heart dimensions during the period since the beginning of the 20th century to nowadays. However, normal values of many other parameters have changed up to 30% over the same period. These changes may be caused by the acceleration phenomenon or the extension of average lifespan. The progress of laboratory medicine methodology permitted the introduction of new biochemical tests in myocardial infarct diagnosis, such as myoglobin and troponins T and I measurement, as well as better understanding of cardiac metabolism. Parameters describing the direction and intensity of metabolic changes are substrate extraction and metabolic equilibrium. The expression describing metabolic equilibrium contains heart mass value. Therefore, as studying heart mass in vivo is not possible, it may be important to study it in vitro. The study was performed on a group of 107 formalin-fixed human hearts. The organs came from adults of both sexes: 30 women and 77 men, aged 18 to 90 years. None of the hearts carried signs of macroscopic developmental abnormalities or pathologic changes.

The morphology of the right atrioventricular valve in the adult human heart.

Studies of the morphometry and normal anatomy of the tricuspid valve are in constant demand. Knowledge of the morphology of the normal tricuspid valve may be useful, for example in the context of the transfer of a leaflet of the tricuspid valve for repair or insufficiency of the mitral valve, in repair of the tricuspid valve after blunt chest trauma and in other surgical techniques of this region. In this study, performed in a group of 107 formalin-fixed adult human hearts, we attempted to assess the form and number of the main and accessory cusps in the tricuspid valve. Rare anatomical variants of the tricuspid valve were found. Using a planimeter we evaluated the surface area of the tricuspid valve and particular leaflets. With the help of a Vernier scale we measured the length and height of individual leaflets of the tricuspid valve and the length of the commissures. No differences were found between the length of the anterior and septal leaflets. The posterior leaflet was the shortest, while the anterior leaflet was the widest and had the largest surface area. The posterior leaflet was wider than the septal leaflet and had the smallest surface area. No differences were found between the main and accessory leaflets in the length of the commissures.

Development of the atrioventricular junctional area in the human heart.

The structure of the heart has been the subject of many observations since the beginnings of medical research. The first information regarding the existence of the conduction system of the heart was described by Purkinje and regarding the a-v node by Tawara. From the history regarding this structure it seems that this special system, so relevant to today's invasive cardiologist, is not understood in full. With regards to the interventional electrophysiology on the basis of histological study we decided to evaluate in detail the morphology and the topography of the various portions of the a-v junction. In order to confirm this hypothesis we made observations on the autopsy material of 100 normal human hearts, both sexes from 16 weeks of foetal life to 105 years of age, in which no pathological changes or inborn faults were found. Sections were done containing the heart's septum, stained using Masson's method with Goldner's modification. This research proves that the atrioventricular junction is a stable structure occurring in all hearts, undergoing involutionary changes with age, in which two main parts can be differentiated: the node and the bundle. The morphology of the node is very complex, because it is composed of three zones: the prenodal, the perinodal and the main, differing in cell structure and position. The topography of the node is generally stable, as it lies in the interatrial septum and always above the septal leaflet of the tricuspid valve. The structure of the bundle, in contrast to the node, is more stable and consists of the following parts: the penetrating, the non-branching and the branching. Its topography is also stable, as it lies in the membranous septum, mainly below the septal cusp of the tricuspid valve.

Myocardial bridges in the human heart: morphological aspects.

The structures made of myocardium running most often above the coronary arteries are called the muscle bridges. However there is a large number of descriptions of that phenomenon, the data are not homogenous. Some papers affirm the occurrence of the clinical implications of their existence. The studied material contained 100 adult human hearts, both sexes, 21 to 76 years of age, preserved in formalin-ethanol solution. Standard anatomical methods were used in analysis with the help of a binocular magnifying glass. The presence of the bridges was confirmed in 41% of the researched material, most frequently above the anterior interventricular branch. The length of the bridges varies in the range of 2.3-42.8 mm, thickness 1.0-3.8 mm, angle between long axis of muscle fibres and long axis of the crossed vessel from 5 degrees to 90 degrees.

The middle cardiac vein as a key for "posteroseptal" space--a morphological point of view.

About 25% of accessory pathways (AP) run via "posteroseptal" space (PSS). There are three approaches for ablation of these pathways: from the right atrium, from the left atrium or from the ventricle and coronary sinus (CS). However in some cases AP is too far from all of them. Catheterisation of the middle cardiac vein (MCV) seems to be the only chance for successful ablation. Our aim was to evaluate the topography of the MCV in PSS. Classical anatomical investigation was carried out on the autopsy material of 98 consecutive human hearts (42 F, 56 M; age 57 +/- 21 yrs). It was supported by transverse section performed under coronary sinus. Regions just behind the atrioventricular septum and behind the cavities were respectively classified as "septal", right (RP) and left posterior (LP). Between them right (RPS) and left posteroseptal areas (LPS) were present. At the posterior view of the heart the angle between CS and MCV ranged from 75 to 90 degrees in 62% of hearts, 60-75 degrees in 18%, 30-60 degrees in 10% and 90-130 degrees in 10%. In 16% MCV ran via the "septal" region, 59%--LPS, 10%--RPS, 10%--RP and 5%--LP. At the ostium of 58% MCV a valve was observed, however there was no trouble with insertion of the 6F catheter into it. We concluded that it is possible to insert the 6F catheter into MCV, which makes it possible to perform ablation of epicardial postero-inferior accessory pathways. The origin of MCV is usually located in the left "posteroseptal" region and runs towards the left side of the posterior wall.

Anterior region of the atrioventricular perinodal area in relation to radiofrequency ablation procedures.

Atrioventricular nodal reentry tachycardia base on reentry circulation in nodal-perinodal area. The radical treatment of choice is radiofrequency ablation. Procedure approached from the anterior-superior (fast) region sufficient a few seconds of energy delivery for success, however this can result in A-V block. The possibility that arrhythmias substrate may lie very superficially (success of ablation) and damage the normal structures (complication) in the perinodal region must be considered. In order to confirm this hypothesis we examined the autopsy material of 100 normal hearts, both sexes from 18 to 105 years of age (control) and 50 hearts with A-V total block 45-95 years of age (block). We paid attention to the morphology of the nodal artery (NA), atrial inputs (AI) and transitional inputs (TI). It was observed that NA at the level of the central fibrous body was positioned in 94% in the central and in 6% in the inferior part of Koch's triangle. It was removed from the endocardium 3-6 mm in control and 2-5 mm in block group respectively (NS). In the perinodal area we distinguished AI that directly joined the A-V compact node: superficial (right part of the interatrial septum) or deep (left part). The former occurred in 100% of controls and in 80% of block groups (NS), and the latter in 80% of control group and in 34% in block respectively (p < 0.05). The real substrate of arrhythmia in anterior-superior region lies very superficially and far from the conduction tissue; NA in examined hearts was lying deep beneath the endocardium; ablation close to the node could result in A-V block.

The valve of the coronary sinus (Thebasian) in adult human hearts.

The observational results of the morphology of the coronary sinus valve are presented in this study. Research was conducted on material consisting of 100 adult human hearts of both sexes from 18 to 87 years of age. Basic morphological types of the examined structure are distiguished and the main traits regarding their histological nature are presented.

Histologic evaluation of the atrioventricular nodal artery in healthy humans and in patients with conduction disturbances.

The anatomy of the conduction system of the heart so relevant in the contemporary invasive cardiology is not fully understood. It has turned out that ablation procedures bring new information as to its structure and function, but in some cases can result in complete a-v block. Atrioventricular nodal artery located within the nodal-perinodal tissue can probably be damaged during the ablation procedures. Therefore, we decided to explore in detail the morphology and the topography of the atrioventricular nodal artery in healthy humans and in patients with clinical traits of a-v conduction disturbances requiring permanent pacing. The microscopic study was carried out on 30 normal human hearts specimens (17 F, 3 M) from 17 to 86 years of age, and on 20 hearts with conduction disturbances (11 F, 9 M) from 39 to 85 years of age. We found that the number of the atrioventricular node arteries is different and independent of the extent that induces block causing conduction disturbances. The topography of the artery in perinodal zone was consistent in normal hearts, yet in hearts with conduction disturbances we observed about 2% of deviations in its location. It might be the reason for generation of iatrogenic complications after invasive cardiological procedures. The morphology revealed changes in 50% of the examined hearts and their vessel walls, which was declared to be connected with ageing. This correlated with certain stages of atherosclerosis as well as hypertension characteristic of elderly patients. We observed that in 33% of hearts from control group small parietal thrombi were detected and in 60% of paced group respectively. Hence, it seems that the procedures in perinodal zone should be performed in its proximal part because of a minor probability of direct and indirect (through nodal artery) damage of the atrioventricular structure of the junction.

Morphology of the tendon of Todaro within the human heart in ontogenesis.

The tendon of Todaro, found in the right atrium of the heart, has considerable clinical importance in the fields of both cardiac surgery and invasive cardiology. The goal of this study was to examine the occurrence and degree of development of the tendon of Todaro in humans. Research was conducted on material consisting of 160 human hearts of both sexes from the age of 14 Hbd to 87 years of age. Classical anatomical methods were used and histological sections were prepared from 100 hearts of various age groups stained with Masson's method in Goldner's modification. The tendon of Todaro occurred in all examined hearts. In foetal hearts, in the area typical of the course of the tendon of Todaro, a very well-developed, white structure was observed, convexed into the lumen of the atrium. Histologically, this was young fibrous tissue with a characteristically large number of fibroblasts. Evenly in infants and newborns, a visible convex structure was also observed extending into the lumen of the right atrium, however, to a lesser degree than in foetuses. In the group of hearts of young adults, it was also possible to follow the course of the tendon of Todaro macroscopically. However, the older the heart was, the less the convex was visible, and in older adults it was completely invisible. In histological sections, it was observed that with ageing the number of connective tissue cells decreased, and fibres forming the lining increased. In the hearts of older adults the tendon of Todaro formed very small ribbons of connective tissue. Histologically, only small numbers of cellular elements were noticed. In the adult heart the examined tendon was located the deepest and did not connect to the endocardium. We can conclude that the tendon of Todaro is a stable structure, occurring in all examined hearts even when it is not macroscopically visible. Due to the morphological changes that affect the tendon of Todaro in human ontogenesis, for the cardiac surgeon, its relevance as an important topographical structure in the hearts of older adults is minimal.